Drill-bit-rotating mechanism for rock-drilling engines.



PATENTED MAR. 27, 1906.

J. GLLEYNE GHANISM FOR 300 DRILL 'BIT ROTATING ME K DRILLING ENGINES.

APPLICATION FILED JUNL 22, 1903.

v 3 SHEETS-SHEET 1.

PATENTED MAR. 27, 1906. 'J. G. LEYNER. DRILL BIT ROTATING MECHANISM FOR ROCK DRILLING E NGINES.

, 3 SHEETS-SHEET 2.

APPLICATION FILED JUNE 22, 1903.

- PATENTEDMAR. 27, 1906.

1 J. G. LEYNBIL, DRILL BIT ROTATING MECHANISM FOR ROCK DRILLING ENGINES.

APPLIOATION FILED JUNE 22, 1903.

- 3 SHEETS-SHEET 3.

To all whom zit/ may concern.-

N E ST T PATENT OFFICE;

"JOHN GE RGE LEYNEK or DENVER,- COLORADO. DRlLL-BIT-FlOTATING MECHANISM FOR RooK-DmL mo. ENGINES.

Be it known that I, J CHEN-GEORGE LEYNER, a c1t1zen of the United States of America, re-

siding in the city and county of Denver and State of. Colorado, have invented certain new and useful Improvements in Drill-Bitart to which it appertains to make and use the same, reference being had to the-accom Rotating Mechanism for Rock-Drilling Enine's; and I 'dodeclare the following to be a l,'clear, and exact descri tion of the invention, such as will enable t ers skilled in the panying drawin' s, and to the figures of ref- 7 its.

through a rock-drilling englne and of my improved drill-bit ste -by-step rotating mechsimple,

a side elevation of erence marked t 'ereon', -which form a part of this specification.

My mvention relates to improvements in novel mechanism for rotating the rock-cut'-- ting drill-bit of rock-drilling engines; second,- to provide a devicefor intermittently rotating the drill-bits of rock-drilling engines .that

I will dispense with the use of a spirally-fluted: rifled bar and the spilirally fluted nut .and' I ratchet-andawl mec anism commonlyused 1n rockdri ing engines for rotating their rock-cutting drill-bits; third, to provide a durable, and efiicient means for rotating the rock-cutting drill-bit of rock-drill-= ing engines. I attainthese objects by the? mechamsmillustrated in the accompanying drawings, in which" Figure 1 represents a top plan'view of a rock-drilling engine embodying my rock-cutting drill-bit-rotating mechanism. Fig. 2

represents a central longitudinal section anism,. showing a rill-bit in operative position in the drillingengine. Fig. 3 re resents Figs. 1 and 2. Flg, 4 is 'arear end elevation. 5 is a section through Fi s. 1 and 2011 me A. Fig. 6 isa section of igs. land 2 on line B. Fig. 7 is a sectional plan view of the. valve-chest on line C of Figs. 2

' elevation of the pawl-actuating iston. Fig.

10 is a cross-section of Fig. 9 on ine D. Fig.

i j "'t1ve v1ew of the drill-bits receivin '-chuck,

, the shank of the drill-bit, and the. ocking-.

collar. Fig. 13 is a section through the rock-' cutting drill-bits locking mechanism on line Patented: March 27, 19.06.

E of Figs. land 2. Fig. 14jis a sideelevation ofa rock-cuttin drill-bit havingits shank formed as I pre erabl use them with myrock-d'rilling en ines.. ig. 15 is a perspective view of the rill-bit? s locking and un-- looking wrenchfand Fig. 16' is a sectional.

view on lineF of Fig. 1.

Similar'numerals of reference refer to similar arts throughout the several views.

eferring to the drawings the numeral 1 designates the cylinder of a compressed-air or other fluid operating rock-drilllng engine, although I wish it distinctly understood that my resent invention relates to an improved device for rotating step by step rock-cutting.

drill-bits and that my invention contemplatesits adaptation to and, use in. 616017110001 motor or .sprm operated or hand-operated rock-drills and m allty'lpes and characters of rock drills and rock-dri ing engines in which the'rock-cutting drill-bit is rotated step by ste while drilling the rock. I

' hecylinder is supported in a gluide-shell v 1, having guideways 1 in which s 'de guides 1, which extend laterally from a depending portion cast upon the bottom of the cylinder.

The mechanism for feeding the cylinder longitudinally through the shell is the" same as that described in my Patent No; 709,022, dated September 16, 1902, and comprises the 'feed screw 2 the operating-handle 2 which is clamped upon the outer end of the feedscrew, a cross-head 2, which supports the handle end of the feed-screw, and the nut 2, through which the feedscrew passes and which is se'cured'in a sleeve 2*, which depends from the rear end of the cylinder, by a shoulder at one end and-a nut'which is threaded to osite end. The cross-head 2 is supby a pair of rods 3*, which are secured 3 formed on opits op porte at their rear ends to ears posite sides of the rear end of the shell-bynuts 3". The rods at their forward ends are bolted to the ends of the cross-head in a similar manner. The free end of the feedscrew extends centrally through the Igio cket of the and 3. Fig. 8 is a sideelevation: of the drill-holding chuck. Fig. 9 is a side shell, and by turning the era -handle the feed-screw is rotated in the cross-headand nut and the cylinder is moved forward or backward through'the shell. adapted to be adjustably supported at any desired angle, and is therefore provided on its under side forward of its'fcenter with a depending hub 4 in the form of a frustum of a The shell is cone, which is in practice secured in a clamping-ring, which in turn is adjustably secured to a horizontal or vertical column, stoppingbar, or tripod, these not being illustrated, as they form no art of the present invention.

The numeral 2 designates the valve-chest, which is formed integral with the cylinder.

Suitable air inlet and exhaust ports 5 and 6 are formed in the cylinder, which extend from the central portion of the cylinder to its opposite ends, and a center port 7, that is positioned between the ports 5 and 6. The ports 5 and 6 connect by lateral ports 5 and 6 with the ports 8 and 9, both of which lead to the front end of the drilling-engine, as will be explained hereinafter. The valve-chest is provided with air-inlet ports 10, 11, and 12 and with exhaust ports 13 and 14. The ports 10, 11, and 12 register with the ports 5, 6, and 7 of the cylinder. A valve 15 is operatively mounted in the valve-chest and is provided with collars 16, which are arranged on a stem 17 to control the ports 10, 11, 12, 13, and 14. The rear end of the cylinder is provided with a rear cylinder-head 18, which is detachably secured to it. An operative piston 19 is reciprocally mounted in the cylinder, which is provided with a circumferential recess 20 at the central portion of its length, which connects with ports 20, 20 20 and 20 to operate the valve. I provide this piston with a hammer-bar extension 21, which I preferably form inte ral with the piston, which projects forwar from the front end of the piston into a sleeve 22, which is rotatably mounted in the axial bore of a tubular-shaped front cylinder-head 23, which is threaded to a stepped portion 24, formed at the front end of the cylinder.

In the front end of the cylinder I form a counterbore of larger diameter than the pistons bore, in which I fit a steel buffer-ring 26, which I term the cylindenring, and against this ring I place a rubber bufler-ring 27, and at the'side of the rubber ring I place a supplementary steel buffer-ring 28, which is positioned in a counterbore 29, which I preferably form larger in diameter than the counterbore in which the rings 26 and 27 are placed. The front end of the cylinder is interiorly threaded, and the front cylinderhead is threaded and screws into it against the shoulder 20, that is formed on the front cylinder-head and up against the ring 28, which acts as an abutment for the bufferrings 26 and 27. cylinder adjacent to the rear cylinder-head a steel buffer-ring 30 is placed in a counterbore 31, against which the piston strikes on its backward stroke. A rubber buffer-ring 32 is placed at the side of the steel buffer-ring and between it and the rear cylinder-head 18.

The front cylinder-head comprises a long cylindrical member, that is adapted to support the rock-cutting drill-bit and its stepby-step rotative mechanism. A transverse cylindrical portion 34 is formed on the cylin- In the opposite end of the drical head intermediate of its ends, the axial bore of which extends at right angles to the axial bore of the cylinder-head. This ri htangled disposed cylinder extends, prefera ly, an equal distance on each side of the axial center of the front cylinder-head. The opposite ends of this cylinder are slightly counterbored and interiorly threaded, and cylinder-heads 37 and 38 are threaded into the ends of the cylinder. In the bore of this cylinder a pawl-carrying piston 39 is slidably fitted. This piston is a little shorter than the cylinder and has but a short stroke therein and is operatively reciprocated by the actuating fluid used to operate the rock-drilling engine, which is preferably compressed air, which flows to the opposite ends of the pawlpiston cylinder from the ports 5 and 6 of the piston-hammers cylinder through the ports 8 and 9, which extend from these ports through the shell of the cylinder and front cylinder-head to the pawl-pistons cylinder. The ports 8 and 9 are arranged on o )posite sides of the main cylinder and exten to the opposite ends of the pawl-piston cylinder, and as these ports are rather crooked I will describe the course of port 8. As the pawlpiston is a small light piece of steelthe power required to reciprocate it in its cylinder is but a trifle. The ports are small passa es, which I preferably make by drilling hoIes in the shell to form the ports, and as both ports are exactly alike, except that the port 9 is alittle longer than the port 8, a description of one will apply to the other. The end 40 of the port 8 is drilled into the shell of the cylinder roin the shoulder at the bottom of the counterbore 25 in the front end of the cylinder. The end portion 40 of the ort 8 is intersected by a short inclined vertical hole 42, which is drilled from the top of the cylinder downward toward the axial center of the main cylinder into the port 8. This vertical portion of the port 8 is intersected by a horizontal hole 43, which is drilled into the front end of the cylinder. The portion 43 of the ort 8 is intersected near the end of the cylin er by a vertically-inclined hole 44, which extends downward from the top of the cylinder and through the same into the front cylinderhead, where its lower end is intersected by a horizontal hole 45, which is drilled into the adjacent end of the front cylinder-head. The hole 45 is intersected by a horizontal hole 46, that is drilled into the side of the front cylinder-head at substantially right angles to the hole 45. The portion 46 is intersected by an inclined hole 47, that is drilled from the top of the front cylinder-head into the pawl-piston cylinder. As the front head screws into the cylinder provision must be made to bring both parts of the hole 44 to connect. I accomplish this by forming short circumferen tial recesses 42 in the periphery of the threaded end of the cylinder-head, which provides anoffsetting passage that ermits a clear 7 passage even if the cylinderead isscrewe'd not .quite to or beyond the position itoccupies when the hole is drilled. The only difference between the port ;8 and the port 9 is that the port-9 extends alon the opposite side of the cylinder and that t e portion 39 of the versely throughits axiallength and which is positioned tosurround the axial center of the main cylinder. This oblong aperture 48 is longest along the length of the pawl-piston,

and in the central ortionof its inner periph ery' recesses 50, an 51 are formed, one at the top portion and one at the lower ortion of the aperture,'1n which are pivotal y-secured and positioned pawls 52 and 53. Suitable springs 54 and 55 are arranged in the piston to bear resiliently on the tooth end of the pawls. Either coiled springs or wire springs or blade-springs maybe used for this purpose, and they may be arranged in any suitable manner; but I preferably use the s ring-wire springs illustrated. One end of e'ac of these sprin s may be secured to the piston by any suita le means, while their op osite ends are arran ed in the recesses an 5]. to bear resilient y against the tops of the pawls. I illustrate 'but two pawls; but more can be -used, if desired. I arrange these pawls and the receiving-recesses in sleeve member which is rotatably mounted in the axial bore of the front :0 linder-head.

The bore of the front cylinde'readis madein two diameters, the inner diameter. being thelargest. vThe chuck is also made two fitting in the lar er diameter ofthe ore in thecylinder an -fitting rotatably between the shoulder at the bottom of the counterbore and the steel'bufler ring. The drill holding chuck is provided with an axial bore of two diameters, 57 A and 57 the bore 57 .ofwhich is the largest and is made to surround loosely the piston-hammer, which recipro The smaller bore 57 of the drill-chuckis" adapted to receive loosely the ihank end of any suitable rock-cutting drillcylinder-head an shank end of the. rock-cutting drill-bits 1n lametrically op site corners of the aperture in the piston. The

p The outer end of the drill-chuck extends slightly begond the end of the front is arranged to receive the such a manner that they are held locked to it and are'rotated by it; but at the same time are free to be inserted into, and withdrawn from it.

In ap lying my drill-bit-rotating device to rock-dri ling engines a number of ways may be employed for arranging the chuck 22 to receive and hold the drill-bits to rotate them a and at the same-time to allow them to-be uickly inserted in and withdrawn from the c uck, and inv the 'diflerent types of rockdrilling engines in use different arrangements ofshanks of drill bits are used and different arrangements of the drill-bit-receiving end of the front cylinder-head are employed, thus necessitatin changes in the arrangement ofthe chuck an its 006 crating ports to hold the drill-bitinrotat-ive yoperativeposition. Consequently my invention contemplates the use of any and all means and devices by which a rock-cutting drill-bit is operatively connected to this chuck to be rotated by it. I preferably, however, use the rock-cutting drill-bit and the cooperating drill-bit-locking device of the end of the front cylinder-head herein illustrated, which is as follows: The outer end of the front cylinder -'head is threaded, a

shoulder 59 is formed at the end of the thread, and a cap 60 is secured upon the threaded portion. The drill-bit-receiving end of the chuck 22 is bifurcated diametrically to form the slots 59 and 60,'(see 12,) and the opposite ends 61 and 62 are provided with step portions 63 and 64 of less diameter, that extend circumferentially around each end about one-half of its semicircular periphery.

The drill-bit 65 consists of a shank portion 66 I and any suitable rock-cutting end portion 67.

The shank is provided adjacent to its end with projecting lugs 68, two referably being used, which are formed on iametrically opposite sides of the shank and are arranged and adapted to slip loosely into the slots 59% and 60 in the. end of the chuck and to bear against the sides of the chuck. The shank of the drill-bit fits loosely in the end or the chuck and its shank 66 extends through the axialbore 57 of the drill-chuck into therediameters and is inserted in the cylinder-head from its 'main cylinder end, its larger ortion move rotativel except when it is moved by* the chuck whic rotates ste by step with the piston and carries the drillit with it, as will be more fully described hereinafter.

The projectin drill-bit are ma e enough shorter than the length .of the bifurcation in the end of the lugs on the "shank of the ochuck to allow the drill-bit a predetermined axial movement of ,about three-eighths to five-eighths of an inch, and in order to confine 3O I pass through the ring-key. The side of the the axial movement of the drill-bit under the var 'ng conditions of the forward feed of the drill cylinder in the shell and the variable forward movement of the drill-bit under the blows of the piston it is necessary to lock it in the chuck in such a manner that it can move axially about this distance independent of the chuc For this purpose I employ a chuck-key69, which is seated in a sleevering 70, that fits loosely in the cap. This ring fits between the end of the front cylinderhead and a steel ring 71, and between this steel ring and the bottom of the cap a rubber buifer ring 72 is placed, which I term the chuck-bufier.

The chuck-key com rises a round narrow ring, which is provide with an axial bore of two diameters 75 and 76. The bore 76 is intersected by diametrically op ositely arran ed axial slots 78 and 79, w ich extend in epth to the surface of the largest axial bore, (see Fig. 12,) in which a perspective view of the chuck-key is shown, thus dividing the smallest diameter of the bore into two,

oppositelyarran ed semicircular lug ortions 80 and 81, t e axial center of whic is provided with the arcs of an axial bore' that is adapted to allow theshank of the drill-bit to extend loosely through the ring-ke while the slots permit the lugs on the drill-bit to ring that faces the chuck bears loosely against the end of the chuck and is provided with two projecting lugs 82 and 83, which are arranged diametrically opposite each other and are adapted and arranged to project loosely over the steps 63 and 64 and to engage the shoulders formed by the junction of these step ortions with the lar er diameter of the en s of the chuck when the chuckkey ring is turned toward them and to strike against the sides 84 and 85 of the oppositelyarranged ends when turned in the opposite direction. When the chuck-key is turned so that its lugs strike the shoulders formed by the steps 63 and 64, its slots are in line with the slot through the ends of the chuck, and the shank of the drill-bit can be inserted into 1ts operative position with its lugs in the slot of the chuck. The key is then turned until its lugs strike the sides 84 and 85, and its Slot will then stand at right angles to the slot inthe end of the chuck and to the lugs on the drill-bit, and the drill-bit Will then be keyed in the chuck against axial displacement, but will still have an axial movement in the chuck suflicient for operative action. The chuckkey can be turned in either direction instantly with the Wrench 86, which is provided at one end with oppositely-arranged rightangled fingers 87 and 88, that are adapted to fit in the slots of the chuck key ring and turn it in either direction. I is not necessary for the operator to look to see if the key-ring is in line with the slot in the chuck when he wishes to insert a drill bit. He simply inserts by hand the shank of the drill-bitin the keyring and chuck, passing the projecting lugs on the shank throu h the radial slots in the key-ring and into t e slot in the end of the chuck. After the shank of the drill-bit has been inserted in the chuck andits projecting lugs have passed through the radial slots in the key-ring should the slot in the end of the chuck-not be in alinement with the lugs a slight turn of the drill-bit by the operators wrist will move the lugs into alinement with the slot, so that they can be inserted. When the slots are in alinement, the side lugs of the key-ring rest close to or substantially a ainst the shoulders 63 64.- at the end of the c huck,

that will rotate the chuck on its'ratchet teeth far enough to bring the shoulders 84 of the chuck a ainst the shoulders 82 83 of the side lugs o the key-ring, which is prevented from rotating with the chuck by the friction of its surrounding ring 72. The drill-bit is then locked to the chuck, as'the slot in the chuck and the projecting'lugs on the drill-bit then stand at ri ht an les to the slots in the key-ring. The drill-bit is thus practically instantaneously inserted and locked by the hand of an operator to the drilling-engine.

To unlock the drill-bit, the right-angled fingers of the wrench 86 are inserted inthe radial slots of the ke -ring and it is turned until itsside lugs stri e the shoulders on the reduced portion ofthe chuck, which brings the slots of the key-ring in alinement with the slot in the chuck, and consequently with the lugs of the drill-bit.

The operation of my rock-cutting drill-bit rotating mechanism is as follows: I have preferably illustrated and described my improved drill-bit-rotating mechanism in operative connection with the valve and ports mechanism of a piston-hammer type or compressed-airoperating rock-drilling engine. This valve mechanism and its operation, as well as that of the piston-hammer, is very clearly illustrated and described in my Patent No. 709,022, dated September 16, 1902, and it is only necessary to mention here that in the preferred construction, which is herein illustrated, the actuating fluid, which may be either air or steam, enters the inlet-port and operativel reciprocates the valve in its chest through the mechanism of the suitable ports and admits air alternately to the opposite ends of the cylinder through the ports 5 and 6, which reciprocates the hammer-piston therein. The air also exhausts through the ports 5 and 6 in alternate order to the atmosphere. As the air passes through the ports 5 and 6 a portion of it enters the ports 8 and 9 in alternate order and flows to the ends of the pawls pistonengage a'ratchet-tooth at the opposite side of the drill-chuck and moves against it on the opposite stroke of the pawl-plston and again turns the chuck a distance equal to the stroke of the piston and pawl. I preferabl make each tooth of the ratchet of the chuck o a little less length than the stroke of the piston, so I that the piawls will surely drop ofi of them at each stro e of the piston and positively turn 5 the chuck. If desired, however, the pitch of the teeth may be made fine enough to permit thepawls to operatively ride over two or more teeth of the drill-chucks ratchet-tooth portion' at each reciprocal stroke of the awls piston. The reciprocative movement the pawlpiston and its pawls thus rotates the drill-holdmg chuc k 'at each stroke of the hammer-piston, as the top pawl 52 is forced to turn the chuck by its piston s movement caused by the -flow of air through the port8 into its 0 linder when the piston-hammer moves bac ward, and the bottom pawl 53 is forced to turn the chuck by the opposite stroke of its piston when the air flows into the port 9 on the for ward stroke of the hammer-piston, thus rotating the drill bit holdin chuck and the ro'ckcutting drill-bit whic is locked to it step by step at each stroke or blow of the piston-hammer. The drill-holding chuck and the drill bit which is locked to-it are thus rotated step by step'at each and every stroke in either direction the hammei-piston makes in its-cylinder by a portion of t e actuatin fluid operatively reciprocating -the paw s piston'in unison with i My invention greatly simplifiesthe mecli used on drilling engines anism commonl for intermittentfiy rotating rock-cutting drill bits. It is also strong, durable, and not liable to get'out of order; I

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a drill-bit-rotating device for rock drilling engines, a suitable casing, a piston reciprocating 1n said casing, an aperture in said Elston, a dull bit holding chuck rotataly su ported in said casing and extending throug the aperture insaid piston, a circular ratchet-tooth band portion on said drillchuck,-spring-controll,ed pawls mounted on said piston in operative relation to the ratchetteeth of said chuck, and means for reciprocating said piston, substantially as described.

' 2. In'a drill-bit-rotating device for rock- 'drilling engines, a suitable supporting-casing, a piston arranged to reciprocate insaid casing and containing an aperture, spring-controlled pawls secured tosaid piston in said aperture, a drill-bit-holding chuck rotatably mounted in said supporting casing and extending through the a erture in said piston, ratchetteeth surroun ing the periphery of said drillholding chuck and positioned thereon in operative'relation to said pawls, a rockcutting ing chuck, a drill-bit adapted to'fit in said chuck, means for attaching said rock-cutting drill-bit to said chuck and means for reciprocating said pistonand pawls to rotate step by step said drill-holding-chuck, substantially as described. v

3. In a drill-bit-rotating device, the combination of a drill-holding chuck rotatably ceive and operatively support and hold a rockcutting drill-bit to rotate it, a iston pro- -vided with an aperturesurroundlng loosely said chuck, means for reciprocating said piston at right angles to the axis of said chuck, a ratchet-toothed peripheral surface on said chuck, spring controlled pawls pivotally mounted in said piston and arranged and adapted to bear in operativemeshing relation on the ratchet-teeth of said chuck and means for reciprocating said piston and pawls to rotatably move step by step said drill-holding chuck and rock-cutting drill-bit, substantially as described. 4. In a drill-bit-rotating device for rockdrillin engines, the combination of the cylinders, the piston-hammer and the front cylinder-head andthe rock-cutting drill-bit, with adrill-holding chuck rotatably mounted in said front cylinder and provided with an axial aperture in which said piston-hammer recip drill-bit in said chuck in striking relation to the ,reciprocal strokes of said piston-hammer, a

surface on said chuck, a block surrounding said chuck loosely, springcontrolled pawls operatively mounted on said block and arthe ratchet-teet -of said chuc and means for'reciprocallymoving said'block and pawls termittently step by step, substantially as described.

5. In a drill-.bit-rotating device for rockdrilling engines, the combination with the cylinder, the valve-chest and valve, the orts in said valve-chest and cylinder, the dril -bitholdin chuck and the rock-cutting drill-bit, of a cy inder arranged transversely across the longitudinal axis of said chuck, a piston in drill-bit-receiving aperture in said drill-hold-' rocates, means for releasably securing said circumferential: ratchet-toothed peripheral to rotatably turn said chuck and drill-bit inmounted and arranged and adapted to reranged and ada tedto bear 0 eratively on 'said chuck positioned within the a erture 1n said piston, and spring-controlle pawls pivotally secured in the aperture in said piston and arranged and adapted to o eratively bear on the ratchet-teeth of said 0 uck, substantially as described.

6. In a drill-bit-rotating device for rockdrilling engines, the combination with the cylinder, and the air inlet and exhaust ports,

of the front cylinder-head detachably secured to said cylinder, the drill-holding chuck rotatably mounted in said cylinder-head provided with a circular band of ratchet-teeth, the piston arranged to reciprocate at right angles to said chuck and provided with pawls arranged and adapted to engage the ratchetteeth of said piston and partially rotate said chuck at each stroke of saidpiston, suitable ports extending from the ports of said cylinder to the opposite ends of said pawl-actuating piston and arranged to operatively reciprocate said piston andsaid pawls to rotate said chuck step by step, and means for rotatably securing a rock-cutting drill-bit to said chuck withln operative striking distance of the reciprocal strokes of said piston-hammer, substantially as described.

7. In a drill-bit-rotating device for rockdrilling engines, the combination with the cylinder, of a drill-holding chuck rotatably mounted in said cylinder-head having a circular row of ratchet-teeth on its peri hery, a block or piston surroundin sai 'chuck loosely, spring-controlled paw s'pivotally secured in said block or piston in operative relation to said ratchetteeth of said drillchuck, means for reciprocating said block or piston and pawls operatively against the ratchet-teeth of saiddrill-holding chuck to intermittently rotate it and means for opera- I tively securing a rock-cutting drill-bit to said cylinder and an operative drill-bit-holding chuck, of a circular ratchet-toothed surface on said chuck, a cylindrical chamber surrounding said chuck and its ratchettooth surface, a piston surrounding said chuck, means including suitable ports for reciprocating said piston in said cylindrical chamber and spring-controlled pawls pivotally secured to said piston in operative bearing relation to said ratchet-toothed surface of said chuck and arranged and adapted to push against the teeth of said chuck and rotate it step by step at each reci rocal stroke of said piston, substantially as escribed.

9. In a drill-bit-rotating device for rockdrilling engines, the combination with the front cylinder-head, of the drill-chuck rotatably mounted in said cylinder-head, having a circular row of ratchet-teeth on its periphery, a block having an oblong aperture therein arranged to permit said block, a transverse reciprocal movement on said chuck, circular recesses extending into one side of said block, recesses in the inner eripheral surface of the aperture in said b ock, a pawl pivotally mounted in each recess and in each peripheral recess in said block and arranged 1n bearing contact with the ratchet-teeth of said chuck, springs secured at one end to said block and arranged to resiliently bear on said pawls, means for reciprocating said pawls to rotate said chuck intermittently step by step, and means for operatively securin rook-cutting drill bits in said. chuck and front cylinderhead, substantially as described.

In testimony whereof I aflix my signature in presence of two witnesses.

JOHN GEORGE LEYNER.

Witnesses:

CLARENCE A. LAWSON, LUTHER H. WYGANT. Jr. 

